Posted on: March 19th, 2019 | By Candy, WayKen Marketing Manager
New product development phase often requires small quantities of trial production and production solutions for design verification, market evaluation. This demand may be dozens, or only one part of the demand.
Automotive development is one typical example in which small initial quantities are needed for validation procedures. There is no doubt that this critical requirement has been a great challenge for parts manufacturers. When the client comes to order a few dozen pieces, it’s often hard to respond, which is why auto suppliers frequently have to turn to custom machined solutions. The clients are in demand of manufacturers who are specialized in custom machining services.
Though traditional, long-lived tools are expensive and are generally not viable for small batch production situations that require only low-volume demands. Professional rapid prototyping companies tend to be the fastest to understand the needs of designers and provide customized machining services to meet the needs of small quantities or even a single part.
Custom Machining Methods and Strategies
Rapid manufacturing technologies are developed to shorten the development cycle of new products at low cost.
1. CNC machining
CNC machining is a CNC machine tool by number of the program with a piece of engraving and milling. CNC milling machine is specially used to process some square, irregular objects, while the lathe is a round object. CNC can process some large workpieces. The maximum can reach 1800*900*600. CNC machining can be a relatively high precision product samples, applied materials mainly include ABS, PC, PMMA, PP, aluminum, copper, etc., often used in making fixture products such as bakelite and aluminum alloy; CNC machining advantage: good toughness, high tension, low cost, and wide selectivity.
When you need to hold tight tolerance(±0.05mm), and when you must have your parts in a specific material, such as metal or the CNC plastic, the services of CNC prototyping are ideal.
2. Vacuum casting
Vacuum casting is wildly used for custom machined parts. The silicone mold has good toughness, there is no draft consideration for silicon mold as it is one of the simplest ways in the rapid tools, with good flexibility and replication performance. It is suitable for low volume trial system to meet certain functional requirements during product development.
Using CNC prototype, silicone mold was produced under the vacuum state, and casting in vacuum by using PU materials, compared to the original sample the casting parts can own a high-temperature resistance, strength, hardness and good copy. If the customer requests a few sets or dozens of sets, it is appropriate to use this method, which greatly reduces the production cost and production cycle.
Vacuum casting parts usually have the feature of shrinkage, generally ±0.25mm/100mm. The cost of casting parts usually is lower than that of CNC machined parts.
3. Rapid tooling for injection molding low volume costumed parts
Rapid injection mold materials are mainly soft steel (for example, P-20) and aluminum (such as 7075 T-6 Aerospace grade aluminum). Compare with hard steel, it can increase the processing speed by 15% to 30%, and the polishing time can be lifted up 3 to 10 times faster with lighter weight, so as to reduce the cost of making mold and shortens the cycle. In addition, rapid aluminum tool facilitates temperature control, allowing faster cycle times and eliminating plastic stress. These materials can be milled to final shape rather than being ground, which cut time and save money as a result. Aluminum has different thermal properties than steel, which must be taken into consideration, but this feature can also cuts costs by eliminating the need for cooling galleries.
Compared with ordinary steel mold, the two materials make almost the same surface quality. The lifespan of aluminum mold is related to the complexity of the product, although far lower than the steel mold, but also can achieve no less than 1000 times of service life, which is more than enough for the initial loading test.
4. SLA / SLS
SLA Prototyping/SLS Prototyping is also known as solid free form fabrication, an additive layering process. A three-dimensional computer model of a part is sliced into layers by the computer program, each slice is fed to a processor in turning laser directs in X and Y axis directions, mean time controlling the beam output power, and cure or sinter through either UV laser (SLA) or CO2 laser (SLS). After the slice is completed the system’s build mechanism vertically reposition incrementally (Z vector), usually between 0.1 mm per layer. This process is repeated until the vertical height of the part is completed. Building time can range from one hour to many hours depending upon the part volume and height.
Post Finish used for Customed Machined Parts
Post finish is one important process for customed machined parts which need rich experiences, including includes manual handling, spray painting (high-gloss, matt, metal paint, rubber paint, pearlescent paint, etc.), silk printing, sandblasting, polishing, electroplating (vacuum plating, water plating), etc.
Manual processing: Polish and fit the samples made, and assemble the parts into a finished product.
Spraypaint: Spray color according to customer’s requirement.
Silk-screen: Print a word or pattern on a sample.
Plating: To make the product more eye-catching, apply the color of the product, which must be very smooth and without impurities, and then soak in the potion. Water – plated features: not easy to scratch, not easy to fade, not bright, the materials needed to withstand high temperature. Vacuum plating features: very bright, and easy to scratch and fade.
Anodizing: The surface of aluminum is oxidized, forming a layer of film, not easy to scratch, not easy to corrode.
UV: Spray a layer of transparent oil on the surface of the sample and dry it with ultraviolet light. The product is brighter and not easy to scratch.
Sanding and polishing: Remove product defects such as a burr, machine line and adhesive mark from the product surface.
Why you Choose CNC Rapid Prototyping Technology?
CNC (Computer Numerical Control) prototype machining is optimal for one-off custom parts and is available in cutting virtually any block material directly according to 3D CAD data. The CNC machined parts can either do certain functional testing or simulate the final product form, including the function form, surface morphology, etc. With a certain intensity of material (such as ABS, PC, etc.), finally it can produce contained the internal structure of the functional model, to test the product structure is reasonable, wall thickness is in accordance with the requirements, the moving parts is smooth, etc.
When you need to hold tight tolerance (±0.05mm), or when you must have your parts in a specific material, such as metal or the CNC plastic, CNC prototyping services are great ideal.
Automotive lighting is the industry widely use CNC rapid prototyping. CNC headlamp prototype machining is characterized as high precision, fast response and short cycle (1-2 weeks of delivery), which makes it possible to machine complex shapes in one piece of material. Usually, in concept stage (conceptual stage) and engineering stage (engineering design stage), it is necessary to make an appearance or function model for a part of the headlight, such as a light pipe or a reflector cup. This demand often requires the ability to produce high-precision prototypes in the shortest cycles with real materials, and CNC is the best choice.
Due to the complicated structure of the lamp, there are many optical details and undercuts, and even high-precision 5-axis CNC can’t process the whole part all at once. CNC programming engineers, who have rich experience in prototype lamp manufacturing, need to analyze the feasibility of machining after obtaining the drawings of the lamp design. For those parts that can’t be processed integrally, they need to provide the solution for disassembly processing, especially for critical surfaces.
In the later stage of prototype production, deburring, polishing, bonding and painting, and other handmade post-processing work is particularly important, will directly determine the final appearance.